Hydrogenation and the magnetic and electrochemical parameters of Nd2Fe12.6T1.4B intermetallides with Nd2Fe14B structures (T series 1 transition metal)
Solid solutions are formed with the Nd2Fe14B structure type when 10% of the iron atoms in the Nd2Fe14B are replaced by series 1 transition metals (Sc, V, Cr, Mn, Co, Ni) or silicon to give Nd2Fe12.6T1.4B. The tetragonal unit cell of the initial structure is almost unaltered.
The chemical nature of the alloying component affects the activity in the interaction with hydrogen for the initial intermetallides, as well as the adsorption capacity and the thermal stability in the hydrides formed. The highest rate of hydride formation occurs for alloys rich in neodymium, which is due to the catalysis by the solid solution of iron in neodymium.
Hydrogenation is accompanied by a rise in Curie temperture of 70–100 K with a simultaneous slight rise in the specific magnetization and a subtantial reduction in the anisotropy field.
The Nd2Fe12.6T1.4B intermetallides are embrittled by hydrogen saturation, which is due to the expansion of the structure by 2–3%, and which enables one to make fine powders with clean unoxidized surfaces. There are thus appreciable increases in the magnetic characteristics of permanent magnets: coercive force, residual magnetization and magnetic energy, which enables one to make high-quality permanent magnets.
KeywordsHydride Polarization Curve Neodymium Iron Atom Anisotropy Field
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- 1.N. F. Chaban, Yu. B. Kuz'ma, N. S. Bilonizhko, et al., “The (Nd, Sm, Gd)-Fe-B ternary system,” Dokl. Akad. Nauk Ukrainy, Ser. A, No. 10, 873–875 (1979).Google Scholar
- 2.C. B. Shoemaker, D. P. Shoemaker, and R. Fruchart, “The structure of a new magnetic phase related to the sigma phase: iron neodymium boride Nd2Fe14B,” Acta Crystallogr.,C40, No. 10, 1665–1668 (1984).Google Scholar
- 4.V. A. Yartys' and A. I. Shtogrin, “Making fine powders of Nd-Fe-B alloy by hydride dispersal,” Fiz.-Khim. Mekh. Mater., No. 4, 111–114 (1988).Google Scholar
- 5.V. A. Yartys', V. V. Burnasheva, and K. N. Semenenko, “The structural chemistry of intermetallic-compound hydrides,” Usp. Khim.,52, No. 4, 529–562 (1983).Google Scholar